Linearly Arranged Multi‐π‐Stacked Structure for Efficient Through‐Space Charge‐Transfer Emitters

• Published in: Angewandte Chemie International Edition Vol. 63; no. 38; pp. e202408712 - n/a
• Main Authors: Qu, Yang‐Kun, Zhou, Dong‐Ying, Zheng, Qi, Zuo, Peng, Che, Zong‐Lu, Liao, Liang‐Sheng, Jiang, Zuo‐Quan
• Format: Journal Article
• Language: English
• Published: WEINHEIM Wiley 16.09.2024; Wiley Subscription Services, Inc
• Edition: International ed. in English
• Subjects: Charge materials; Charge transfer; Chemistry; Chemistry, Multidisciplinary; C−H activation; Emitters; Fluorene; Light emitting diodes; Molecular structure; Optoelectronics; Photoluminescence; Photons; Physical Sciences; Quantum efficiency; Rigid structures; Science & Technology; Space charge; Spiro compounds; Thermally activated delayed fluorescence; Through-space charge transfer; π-Stacked structure; Thermally activated delayed fluorescence; LIGHT-EMITTING-DIODES; DESIGN; C-H activation; pi-Stacked structure; ACIDS; RING; Through-space charge transfer; ACTIVATED DELAYED FLUORESCENCE; Spiro compounds; C−H activation; π-Stacked structure
• ISSN: 1433-7851; 1521-3773; 1521-3773
• DOI: 10.1002/anie.202408712

Noncovalent spatial interaction has become an intriguing and important tool for constructing optoelectronic molecules. In this study, we linearly attached three conjugated units in a multi π‐stacked manner by using just one trident bridge based on indeno[2,1‐b]fluorene. To achieve this structure, we improved the synthetic approach through double C−H activation, significantly simplifying the preparation process. Due to the proximity of the C10, C11, and C12 sites in indeno[2,1‐b]fluorene, we derived two novel donor|acceptor|donor (D|A|D) type molecules, 2DMB and 2DMFB, which exhibited closely packed intramolecular stacking, enabling efficient through‐space charge transfer. This molecular construction is particularly suitable for developing high‐performance thermally activated delayed fluorescence materials. With donor(s) and acceptor(s) constrained and separated within this spatially rigid structure, elevated radiative transition rates, and high photoluminescence quantum yields were achieved. Organic light‐emitting diodes incorporating 2DMB and 2DMFB demonstrated superior efficiency, achieving maximum external quantum efficiencies of 28.6 % and 16.2 %, respectively. Through‐space charge‐transfer materials excel in organic light‐emitting diodes, with π‐stacked structures being effective frameworks, but the lack of robust construction methods hinders progress. Double C−H activation has now been used to construct two donor‐acceptor‐donor (D|A|D) type through‐space charge‐transfer materials derived from C11‐substituted indenofluorene skeletons, with maximum external quantum efficiencies of 28.6 % and 16.2 % achieved.